The additions of the oil and gas drillers are expected to create a natural resources conglomerate with assets ranging from oil rigs in the Gulf of Mexico to mines in Indonesia and Africa.

Freeport will buy Plains Exploration Co. for $50 per share in cash and stock totaling $6.9 billion. It will acquire McMoRan Exploration Co. for $14.75 per share in cash, or about $2.1 billion excluding interests already owned by Freeport and Plains.

McMoRan Exploration shareholders will also get a distribution of units in a royalty trust.